1. Field of the Invention
The present invention relates to a preceding-vehicle identifying apparatus and a following-distance control apparatus.
2. Description of Related Art
It is known to mount an ACC system (Adaptive Cruise Control system) which uses a scanning sensor on a vehicle for easing a vehicle driver's burden. The ACC system automatically controls the vehicle speed of an own vehicle at a set speed, and automatically controls the following distance (the distance to a preceding vehicle) detected by the scanning sensor at a predetermined distance. That is, the ACC system operates to decrease the speed of the own vehicle when the speed of the preceding vehicle is smaller than the set speed by causing the brake to apply to keep the following distance the same, and increases the speed of the own vehicle up to the set speed after the preceding vehicle disappears.
There is known a method performed in such an ACC system for predicting the course of the own vehicle using a curve curvature calculated based on the yaw rate of the own vehicle, and identifying a vehicle present on the predicted course of the own vehicle as a preceding vehicle. For example, refer to Japanese Patent Application Laid-open No. H11-045398.
However, the method described in this patent document has a problem in that the identification of a preceding vehicle may not be performed correctly due to a difference between the predicted course of the own vehicle and the course of the preceding vehicle caused by a difference in running position between the own vehicle and the preceding vehicle. This problem becomes conspicuous when there is a curved road ahead of the own vehicle.
If it is erroneously determined that there is no preceding vehicle due to the above problem, it may occur that the speed of the own vehicle is unnecessarily increased causing the following distance to be decreased, and the behavior of the own vehicle feels unnatural to the vehicle driver. Further, if it is erroneously determined that there is an preceding vehicle due to the above problem, it may occur that the speed of the own vehicle is unnecessarily decreased, and the behavior of the own vehicle feels unnatural to the vehicle driver.